Abdominal Mass
Marc H. Gorelick
INTRODUCTION
In children, abdominal masses present in variable ways. Some produce symptoms or signs; others remain silent even when large. An abdominal mass may be discovered by a parent or caregiver, or it may be an incidental finding during physical examination. The age of the child is an important factor in the differential diagnosis. Most masses discovered in neonates are benign, whereas up to 50% of masses in older children are malignant (Table 8-1). Table 8-2 lists the most common sites of origin of abdominal masses according to the age of the patient.
HINT: In newborns, the bladder is an abdominal organ.
HINT: An abdominal mass in a neonate is usually renal in origin—hydronephrosis and multicystic kidney are the most common causes of abdominal mass in neonates.TABLE 8-1 Common Abdominal Masses | ||||||||||||||||||||||||||||||
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DIFFERENTIAL DIAGNOSIS LISTInfectious Causes
Appendiceal abscess
Tubo-ovarian abscess
Hepatic abscess
Perinephric abscess
Neoplastic Causes
Malignant
Wilms tumor (nephroblastoma)
Neuroblastoma
Lymphoma
Rhabdomyosarcoma
Rhabdoid tumor
Hepatoblastoma
Sarcomas (retroperitoneal and embryonal)
Ovarian tumor
Metastatic disease
Benign
Ovarian teratoma
Sacrococcygeal teratoma
Mesonephric blastoma
Traumatic Causes
Perinephric hematoma
Pancreatic pseudocyst
Adrenal hematoma
Duodenal hematoma
Congenital or Vascular Causes
Cysts—ovarian, choledochal, hepatic, mesenteric, urachal
Hydrometrocolpos or hematocolpos
Anterior myelomeningocele
Renal vein thrombosis
Hepatic hemangioma
Gastrointestinal System Causes
Gastrointestinal (bowel) duplication
Constipation
Pyloric stenosis
Hepatitis
Intestinal distention—intussusception, imperforate anus, Hirschsprung disease, volvulus, meconium ileus
Gallbladder hydrops
Genitourinary System Causes
Hydronephrosis
Polycystic or multicystic kidney
Ectopic or horseshoe kidney
Posterior urethral valves
Distended bladder
Pregnancy (intrauterine or ectopic)
TABLE 8-2 Sites of Origin of Abdominal Masses | |||||||||||||||
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HINT: The patient’s age is an important key in helping narrow down the possible differential diagnosis of an abdominal mass because its causes differ among neonates, infants, and children.DIFFERENTIAL DIAGNOSIS DISCUSSION
Appendiceal Abscess
Etiology
Untreated acute appendicitis leads to perforation with abscess formation.
Clinical Features
A child with an appendiceal abscess appears generally ill. Fever and abdominal pain are common symptoms. Although many children have a history highly suggestive of appendicitis (see Chapter 9, “Abdominal Pain, Acute”), others have an atypical history characterized by a subacute course, with symptoms present for days to weeks.
HINT: Patients (especially young children) with appendiceal abscess may not show typical abnormalities associated with appendicitis, such as anorexia and peritoneal signs.Evaluation
A tender mass is located in the right lower quadrant, and signs of peritoneal irritation are often, but not invariably, present. The mass may be palpable on rectal examination. In postpubertal females, a pelvic examination is important to exclude pelvic inflammatory disease.
Leukocytosis with a left shift is a helpful supportive finding. If the diagnosis of appendicitis is clear, additional studies are unnecessary. In difficult cases, an abdominal radiograph may provide confirmatory evidence (e.g., a fecalith, present in <10% of cases, free intraperitoneal air, or a right lower quadrant mass effect with ileus); however, ultrasound is the diagnostic study of choice.
